[Yuffie Kisaragi]

I haven't really heard of Kuja being a female in Japanese either, but it's likely that he COULD be since the American government is very particular about that kinda stuff (morons, it's life, get over it -.-). But we can confirm he was a male in the American version at least, cuz Zidane and other character refer to Kuja as "he" and other male pronouns.